public void TestPrependToElement()
{
var content = new HElement("span", "Content");
var element = new HElement("div", "First Content");
Assert.Same(content, content.PrependTo(element));
Assert.Equal("<div><span>Content</span>First Content</div>", element.ToString());
Assert.Same(content, content.PrependTo(null));
content = null;
Assert.Null(content.PrependTo(element));
}